1. Field of the Invention
This invention relates to a structure for mounting an EMI prevention filter onto an electric wire.
2. Description of the Related Art
In recent years, in the field of electronic apparatus such as communication apparatus, an increase in amount and speed of information to be processed has increased remarkably,.and EMI (Electromagnetic Interference) caused by electromagnetic waves radiated from or admitted into such electronic apparatus makes a problem. Therefore, various countermeasures for prevention of electromagnetic waves are provided for such apparatus themselves, and in order to prevent electromagnetic waves from entering into or being radiated from an electronic apparatus by way of an electric wire connected to the electronic apparatus, an EMI prevention filter is mounted on the electric wire. Such EMI prevention filter is constituted from, for example, a pair of core members having such shapes as are obtained by dividing a cylinder along a plane passing an axial line of the cylinder. The inner diameter of a core constituted from the core members is substantially equal to the diameter of the electric wire on which the core is to be mounted. The core is made of a metal depending upon an applicable frequency or the like, such as, for example, ferrite.
In one of known mounting structures for an EMI prevention filter, such a pair of core members as described above are disposed in the proximity of a connector to an electronic apparatus provided at an end portion of an object electric wire in such a manner as to hold the electric wire from the opposite sides and are banded to the electric wire, for example, using a nylon band to mount the core onto the electric wire. In another known mounting structure for an EMI prevention filter, such a pair of core members as described above are hinged at side edge portions thereof for pivotal motion relative to each other while locking means are provided on the other side edge portions, and an object electric wire is held from the opposite sides thereof in a similar manner by and between the core members and the core members are locked by the locking means to mount the core onto the electric wire.
However, since the diameter of an electric wire onto which an EMI prevention filter is to be mounted has a wide variety of values, the configuration of an EMI prevention filter prepared in advance may not sometimes conform to that of an object electric wire. In such an instance, where the EMI prevention filter has any of such conventional structures as described above, it may be difficult to mount the EMI prevention filter onto the electric wire or the EMI prevention filter may be dislocated on or may drop from the electric wire as time passes. Consequently, the conventional mounting structures for an EMI prevention filter is low in reliability. Further, in order to prevent EMI, an EMI prevention filter to be mounted must necessarily have a characteristic which matches with a frequency of electromagnetic waves which may be radiated from or enter into the electric apparatus. However, since mounting of an EMI prevention filter is performed in a trial and error fashion at a site, that is, in an office, a factory or the like in which the electronic apparatus is installed, the EMI prevention filter is required to be mounted and dismounted easily. Further, even when an EMI prevention filter is to be replaced with another EMI prevention filter of a different profile, such replacement should be performed readily.